The carnage caused by fertiliser bombs

Fertiliser-based explosives have proved their deadly effectiveness in a series of horrific terror attacks around the world.

Provisional IRA units used the substance in bombing campaigns in Northern Ireland and against targets in London in the 1990s.

IRA members referred to it as “Co-op Mix” because of the ingredients’ wide availability.

In the new age of Islamist terrorism, ammonium nitrate fertiliser packed into a truck with plastic explosive as a detonator has also become an al Qaida trademark.

The Muslim terrorists’ desire to cause maximum loss of life means the fertiliser bomb’s true capacity for carnage has become horribly apparent.

Although Northern Ireland terrorists’ coded warnings were erratic and unreliable – most infamously with the 1998 Omagh bombing – the Provisionals did usually offer some tip-off of an imminent blast.

In comparison, al Qaida has deliberately driven victims in the direction of a blast – notably in the 2002 Bali bombings which claimed 202 lives, including 28 Britons.

Seven men were accused at the Old Bailey of conspiring to create an explosion at a major British target using 1,300lb (600kg) of fertiliser, which they had stored in a west London lock-up.

Mark Heywood, for the prosecution, said a handbook discovered on Jawad Akbar’s computer gave detailed instructions on how to make a bomb from fertiliser which was so strong it would “make the ground shake”.

If all the fertiliser had been used in one device, at just under two-thirds of a ton, it would have been comparable in size to the IRA’s Docklands bombs, and to the abortive attempt to bring down the Twin Towers in Manhattan in 1993.

Explosives expert and editor of NBC (Nuclear, Biological, Chemical) International, Andy Oppenheimer, said: “You would have been talking about absolute mayhem if they had aimed for an enclosed space rather than an open-air target.

“They would have had the ability to kill hundreds of people.

“They would probably have made the biggest explosion in mainland Britain since the Manchester bomb in 1996.”

Mr Oppenheimer, who is writing a book on the IRA’s bomb technology, added: “Using 600 kilos in one truck bomb would result in a pretty big area of destruction.

“The actual explosive yield would depend on how well the fertiliser had been milled and prepared – which was something at which the IRA were very proficient. And you can get one hell of a bang.”

Jurors at the Old Bailey trial were shown a video of a mock-up bomb recreated by National Grid engineers, simulating attacks on the gas pipeline network.

The engineers used plastic explosives and then recreated a homemade bomb consisting of ammonium nitrate fertiliser and diesel fuel.